PROMINENTS. 119 
forked tail, which takes the place of the hindmost pair of 
legs, is not used in creeping, but is used as an organ of 
defense. It consists of two movable hollow tubes, within 
each of which is concealed a long orange-colored thread or 
flagellum, which the insect can push out and draw inat will. 
If the caterpillar is disturbed it suddenly erects and separates 
the two tubes, and pushes out the brightly colored whip- 
like threads, which, as they lash any intruder, give off at 
the same time a peculiar odor, no doubt offensive to the 
same. The caterpillar of borealis feeds upon the wild cherry 
and other allied plants. Its head is reddish-brown. The 
first very broad segment is square in front on the sides, and 
ends in a low projection, which looks somewhat like the 
hood of amonk. The body is pale yellowish-green, with a 
dorsal median reddish-brown band, beginning at each angle 
on the first segment, and narrowing on the second and 
third segments, it begins to widen again on the fourth, be- 
coming widest on the seventh, and extending down each side 
near the base of the abdominal legs; it contracts and be- 
comes narrowest on the end of the tenth segment, and 
widens a little on the last. The red patch is sometimes 
more or less interrupted bythe ground color. Theanal-plate 
is triangular, rounded at end; the tails are long, brown, 
with three pale rings on the outer half. Thoracic feet deep 
red; abdominal legs pale, tips reddish. 
The caterpillars eat a flat depression into wood, over 
which they spin an oval cocoon, mixed with particles of 
wood. This cocoon is difficult to detect and very hard. 
The moth has a white head and thorax, the latter being 
bluish-black in the center. The fore-wings are white, with a 
very broad grayish-black median band with irregular edges, 
contracting about the middle. Outside is a blackish shade 
across the wing. The space between the band and shade is 
white, with two distinct black spots on the costa, followed 
by two rows each of four small spots. The outer and basal 
parts of the wings are white, the former with a terminal 
